In the radiotherapy industry, the technology of using Go-60 for focused radiotherapy is quite well developed. However, due to the intense radiation of Go-60 radioactive sources, a very thick and heavy shielding structure should be set up to a radiotherapy equipment, to prevent radiation leakage. Moreover, a traditional focused treatment head, which is part of the radiotherapy equipment, generally adopts the structure of shielding part, source part and collimation part sequentially arranged from the outside to the inside, so that the structure of the focused treatment head is very complicated and bulky. In addition, the focused treatment head usually requires as many collimator combinations as possible to obtain more collimation aperture combinations to meet different field sizes and dose requirements. However, regardless of rotatable collimation structure or translational collimation structure, the number of collimators that can be selected is limited due to the treatment space limitations, which greatly reduces the flexibility for the focused treatment head in clinical use.